1. Field of the Invention
The present invention generally relates to a continuously variable transmission of an automotive vehicle, which transmission comprising a V-belt type continuously variable transmission mechanism, a start assist device, a forward-reverse changeover device and a casing. More particularly, the invention relates to a fluid passage arrangement for the continuously variable transmission, which arrangement serving to supply pressurized hydraulic fluid and lubricating fluid to at least the transmission mechanism and the forward-reverse changeover device.
2. Description of the Related Art
A continuously variable transmission of the above-mentioned type is known from Japanese patent application laid open No. 1-112076, which patent application being filed by an applicant of the present application.
In the known continuously variable transmission, the V-belt type continuously variable transmission mechanism has a drive pulley, a driven pulley and an endless V-belt, each width of V-grooves of which pulleys being changeable for continuously varying a rotational speed ratio between the pulleys by supplying pressurized hydraulic fluid to actuate a piston in a hydraulic fluid chamber of at least the drive pulley, and between which drive and driven pulleys the V-belt being passed for transmitting power between the pulleys. The forward-reverse changeover device has a planetary gearing, a forward clutch, a reverse brake and an input shaft, which planetary gearing receiving rotational power from the start assist device through the input shaft and providing the rotational power to the drive pulley of the transmission mechanism through a drive shaft connected to and carrying the drive pulley, and which planetary gearing changing over a rotational direction of the drive shaft between the same and a counter direction relative to a rotational direction of the input shaft by selectively actuating the forward clutch or the reverse brake. The start assist device transmits rotational power between an engine as a power unit and the forward-reverse changeover device, allowing rotation of an output shaft of the engine despite of stop rotating condition of the input shaft.
The known continuously variable transmission further comprises a differential gearing device for driving front and/or rear wheels of an automotive vehicle, which differential gearing device being drivably connected to the driven pulley through a gearing. Thus, the continuously variable transmission is capable of transmitting rotational power from the engine to the wheels, with a desired rotational speed ratio and a desired rotational direction.
The transmission mechanism, the start assist device and the forward-reverse changeover device are contained in the casing. The casing consists of a housing, a casing body and a side cover, all of which being connected to each other by bolts. The housing contains the start assist device, while the casing body contains the continuously variable transmission mechanism and the forward-reverse changeover device in such a manner that the input shaft of the forward-reverse changeover device and the drive shaft of the drive pulley are aligned along a common longitudinal central axis, the drive shaft of the drive pulley and a driven shaft connected to and carrying the driven pulley are placed parallel to each other, the planetary gearing of the forward-reverse changeover device is placed in a radially outer peripheral space with respect to the input shaft, surrounding the input shaft, and the the drive shaft and the driven shaft are rotatably supported by the casing body. The side cover is placed at an opposed end of the casing with respect to the housing, rotatably supporting both of an end of the drive shaft of the drive pulley and an end of the driven shaft of the driven pulley.
The fluid passage arrangement, contained in the casing, includes hydraulic fluid passages for supplying pressurized hydraulic fluid into the hydraulic fluid chamber of the drive pulley, and lubricating fluid passages for supplying lubricating fluid into the forward-reverse changeover device.
The hydraulic fluid passages for the drive pulley are arranged in such a manner that a fluid passage is formed in a wall of the casing body and connected to a pressurized hydraulic fluid supply, a pipe as another fluid passage is fixed on a wall of the side cover at inside of the side cover and connected to the fluid passage in the wall of the casing body, an axial hole as another fluid passage is drilled in the drive shaft of the drive pulley and connected to the pipe on the side cover, and a through hole as another fluid passage is drilled in the drive shaft so that the through hole extends between the axial hole of the drive shaft and the hydraulic fluid chamber of the drive pulley.
The lubricating fluid passages for the forward-reverse changeover device are arranged in such a manner that an axial hole as a fluid passage is drilled in the input shaft and connected to a lubricating fluid supply, and a through hole as another fluid passage is drilled in the input shaft so that the through hole extends from the axial hole of the the input shaft toward the planetary gearing, the forward clutch and the reverse brake.
The fluid passage arrangement further includes other lubricating fluid passages for supplying lubricating fluid to many bearings, which bearings being provided for rotatably supporting the drive shaft and other rotational components of the forward-reverse changeover device and the transmission mechanism. However, the lubricating fluid passages for the bearings are arranged relatively complicatedly, accompanied with increased manufacturing cost.
Moreover, since the pipe as a hydraulic fluid passage is arranged at inside of the side cover, the side cover is bulged axially outwardly, so that the continuously variable transmission has a relatively large axial size, causing difficulty of mounting the transmission on a small size automotive vehicle.